Buchmann Christian, Rudolph Simon, Neff Janina, Steinmetz Zacharias
IES Landau, Institute for Environmental Sciences, Group of Soil and Environmental Chemistry, RPTU University Kaiserslautern-Landau, Landau, Germany.
Sci Rep. 2025 Jun 3;15(1):19422. doi: 10.1038/s41598-025-04457-8.
Polyacrylic acid (PAA), a synthetic superabsorbent polymer (SAP), enhances the maximum water holding capacity (WHC), soil structural stability, and aeration of soil but may simultaneously affect soil microbiome by altering soil properties. However, its effects on microbial activity under different moisture regimes remain insufficiently understood. We examined the impact of PAA on soil microbial activity in a sand and loam treated with PAA at three concentrations (25, 250, 2500 mg kg dry soil) either incubated under constant moisture or subjected to ten drying-rewetting cycles. During incubation, soil WHC, pH, and soil microbial activity via headspace CO and MicroResp assay were measured. PAA increased WHC in both soils, yet its effectiveness decreased in loam under static conditions. Initially, PAA acidified both soils, with pH shifts persisting in sand but dissipating in loam after one week. Drying-rewetting cycles counteracted acidification and partially maintained PAA swelling. In sand, high PAA concentrations consistently suppressed microbial respiration across substrate groups, whereas in loam, microbial responses were modulated by moisture dynamics: drying-rewetting enhanced, while static moisture reduced SIR under PAA treatment. Overall, PAA altered soil microbial activity in a concentration-, soil type-, and moisture-dependent manner, emphasizing the dual role of SAPs in improving soil water retention while potentially impairing microbial-mediated soil functions over time.
聚丙烯酸（PAA）是一种合成高吸水性聚合物（SAP），它能提高土壤的最大持水量（WHC）、土壤结构稳定性和通气性，但可能会通过改变土壤性质同时影响土壤微生物群落。然而，其在不同水分条件下对微生物活性的影响仍未得到充分了解。我们研究了在三种浓度（25、250、2500毫克/千克干土）的PAA处理下，砂质土和壤土中PAA对土壤微生物活性的影响，这些土壤要么在恒定湿度下培养，要么经历十次干湿循环。在培养过程中，通过顶空CO和微呼吸测定法测量土壤的持水量、pH值和土壤微生物活性。PAA提高了两种土壤的持水量，但在静态条件下，其在壤土中的效果有所下降。最初，PAA使两种土壤酸化，砂质土中的pH值变化持续存在，而壤土中的pH值变化在一周后消散。干湿循环抵消了酸化并部分维持了PAA的膨胀。在砂质土中，高浓度的PAA持续抑制所有底物组的微生物呼吸，而在壤土中，微生物反应受水分动态调节：干湿循环增强了微生物反应，而在PAA处理下，静态水分降低了底物诱导呼吸（SIR）。总体而言，PAA以浓度、土壤类型和水分依赖的方式改变土壤微生物活性，强调了高吸水性聚合物在改善土壤保水能力方面的双重作用，同时随着时间的推移可能会损害微生物介导的土壤功能。
